Changes in myocardial electrolytes and ventricular fibrillation threshold induced by alcohol feeding in laboratory rats.

Three groups of rats were studied in an investigation to determine the influence of alcohol on myocardial electrolytes and the ventricular fibrillation threshold (VFT) levels. Drinking water was provided ad libitum; the control group received water while the other 2 groups drank a water-ethanol solution, constituted in a ratio of 75: 25, for periods of 3 and 9 months, respectively. Two rats from each of the experimental groups, together with a control rat were killed on each experimental day. One heart was studied on the Langendorff preparation and the other used for tissue electrolyte analysis. The mean myocardial Mg2+ levels (233 +/- 28 micrograms/g vs 148 +/- 23 micrograms/g and 233 +/- 28 micrograms/g vs 107 +/- 15 micrograms/g; p less than 0.0001), K+ levels (3260 +/- 437 micrograms/g vs 1779 +/- 312 micrograms/g and 3260 +/- 437 micrograms/g vs 1195 +/- 205 micrograms/g; p less than 0.0001) and Zn2+ levels (32.7 +/- 6.8 micrograms/g vs 14.0 +/- 4 micrograms/g and 32.7 +/- 6.8 micrograms/g vs 4.2 +/- 3.4 micrograms/g; p less than 0.0001) were significantly lower in alcohol fed rats than the controls. In addition, a significant fall in the mean VFT levels (10.1 +/- 1.94 mA vs 6.27 +/- 2.17 mA, p less than 0.001) was noted in rats given water: alcohol solution for 9 months. This study reveals that chronic exposure to alcohol induces a deficiency of myocardial Mg2+, K+ and Zn2+, and an increase in myocardial irritability in laboratory rats.